I really don't agree with that. Everything else you said was spot-on, but in my opinion the Obi-Wan we see in the OT flows naturally from that. I think that Obi-Wan was certainly not in denial in the OT about what happened to Anakin at all. "Vader was seduced by the dark side of the Force." That line couldn't have been clearer. Even in the original film, the young Vader was established as a pupil of Kenobi's who Kenobi had once thought was good. The quoted line indicates a fall from the good side to the bad side. As such it's an admission that Vader is now evil. If we accept that these lines are to be read with the understanding that they refer to Anakin, then implicitly they indicate an acceptance by Obi-Wan that Anakin has fallen into evil.
What I meant by that isn't so much that Kenobi is in denial about what happened to Anakin, but what Anakin *did*. "Betrayed", "murdered", "seduced". These are all external actions and paint Anakin as a victim of one sort or another. I think perhaps there's a part of Obi-Wan that just can't cope with the notion that Anakin consciously chose the "let's go murder all the younglings" option. That Vader is somehow a different person that lives in his brain and just took over one day because evil Chancellor Palpatine did his evil seduction thing (OK, that sounds a lot dirtier than I'd intended...) Where in reality, "Vader" was there the whole time, growing. And Obi-Wan never saw it for what it was.
The prequals weren't as horrible as many fans made them out to be. However , IMO, they were a huge step down from the OT and made me realize how important people like kerschner, Kasdan, editors, etc were to those films. Whenever I do a Star Wars marathon for pre-OT I only include the ROTS along with Rogue One.